Relaxation oscillators have become increasingly common in microelectronics. Some examples of conventional designs can be found in U.S. Pat. Nos. 6,020,792; 6,201,450; 6,337,605; 6,456,170; 6,924,709; and 7,138,880. These oscillators oftentimes use a signal that has a generally triangular waveform that is input into a pair of comparators. FIG. 1 depicts an ideal triangular waveform, where the signal is confined between two reference voltages.
However, as speeds increase and as real-world effects become apparent, the signals can stray away from their idealized forms. Some of the real-world effects that can affect the operations of relaxation oscillators are delays present in some of the components, such as latches and comparators. FIG. 2 depicts a voltage versus time graph depicting a triangular waveform for a relaxation oscillator with delays. As can be seen in FIG. 2, the triangular wave overshoots the upper voltage (V1) by a small amount (δ1) and undershoots the lower voltage (V2) by a small amount (δ2), each of which can be attributed to delays present in the circuit. Additionally, these voltage differences (δ1 and δ2) are not necessarily static, but in fact, can vary depending on a number of factors, including temperature, which can cause the frequency and period of the triangular waveform to vary.
Therefore, there is a need for a method and/or apparatus to compensate for circuit delays.